English Oak , Common Oak, Tanner's Bark (1, 7).
Dried bark of branches, trunk and shoots; dried leaves and seed kernels with seed coats removed (8); also bark and galls (1, 5, 7).
Quercus robur is widely distributed throughout Europe (5, 7) and England (7). It is a deciduous tree reaching 45 metres with leaves which are deeply lobed (5) and flowers of two kinds; the male, or barren, in long drooping catkins 2 to 8 cm long (5, 7) appearing with the leaves, and the fertile flowers and leaves found in distant clusters (7). The fruit produced is an acorn approximately 1 to 3 cm long and appearing in shades of green to brown (5, 7).
The genus name Quercus comes from a Celtic word, quer, meaning ‘fine’ and cuea, meaning ‘tree’ (1). The oak, for many centuries was the chief forest tree of England, and is closely bound up with the history of Druid times (1, 5, 7). Believed to be sacred, the oak was used to tan leather and smoke fish (5) and a spray of oak was engraved on one side of sixpences and shillings (7).
Traditionally Quercus robur has had many uses. Owned by Jupiter the bark was used to stay the spitting of blood and a decoction used to prevent vomiting (9). Numerous references are made to its cooling action and it was used internally or externally for inflammation (9). It is known as one of the best remedies for inflammation of the eye (10), and was implicated for use in exhausting night sweats, and fevers as a substitute for quinine (7, 9, 11). It was also said to have a cooling effect upon the liver (9).
Reference to its use in the urinary system and upon kidney function are present in historical texts, where the acorn powder taken in wine was said to promote urine (9), the bark to cause weak stimulation of the renal and lower urinary system (12), and act as a tonic upon the kidneys (13).
Reference to its use on the skin is revealed in numerous historical texts where water found in the hollow places of old oaks was said to be effectual against the spreading of foul scabs (9), a decoction applied to ulcerations with unhealthy, fetid discharges or spongy granulations (4, 10, 11), or for the treatment of gangrene (4, 11). It was also known to act as a tonic upon the skin (13).
An affinity for treatment of the oral cavity is noted with reference to its use in cases of bleeding of the mouth (9), ulcerated and putrid sore throats (4, 11, 14) and as a gargle in aphthous sores (14). Other various documented uses include diphtheria (14), cholera (10, 11), marasmus, scrofula, diabetes, menorrhagia, obstinate intermittents (11) and to purge worms (10). A wash of oak bark was also used for a prolapsed rectum or a 'falling of the bowels', where a portion of the bowels protrudes from the anus (4, 10).
Weak suppression of the upper and lower gastrointestinal tract was historically noted of Quercus robur (12) and a distilled water preparation was known as one of the best remedies for milky vaginal discharges in women (9). Also used historically for the treatment of advanced breast cancer, a wash of oak bark tea was applied to the area of tumour growth (10).
Quercus robur additionally played a role in convalescence and was used in incidences of great exhaustion of the vital powers from disease and debility to restore the fading powers of life (11). A decoction of the acorns and the bark in milk was also used as an antidote to poisonous herbs and medicines (9). In terms of its preparations it is noted historically that water extracts its qualities fully, whereas diluted alcohol works less fully (14).
Major Active Constituents
- 15-20% Tannins (1, 2, 3, 4, 5, 6, 11, 15), including gallic acid (1, 3, 5, 16, 17), and ellagitannins (1, 3, 5);
- Galls contain approximately 50% tannins (5, 7);
- Flavonoid glycosides (16).
A study from 2000 analysed extractable tannins in Quercus robur. Results showed tannins isolated mainly included various glucose gallic and ellagic acid esters. The structures were partially determined, and they included grandinin/roburin E, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercitrin and ellagic acid (24).
A later study in 2004 looked at the seasonal variation in the phenolic content of Quercus robur. Seven different trees were followed over the full course of the growing season, and their foliage repeatedly sampled for gallic acid, 9 individual hydrolysable tannins, and 14 flavonoid glycosides, as well as for total phenolics, total proanthocyanidins, carbon, and nitrogen. From the study a rare dimeric ellagitannin, called cocciferin D2, was detected for the first time in leaves of Quercus robur and overall, hydrolysable tannins were the dominant phenolic group in leaves of all ages. Young oak leaves were found to be much richer in hydrolysable tannins and flavonoid glycosides than old leaves, and the pattern reversed for proanthocyanidins. When measured as individual compounds, hydrolysable tannins and flavonoid glycosides showed highly variable seasonal patterns (16).
- Astringent (3, 6, 7, 9, 17, 18)
- Tonic (4, 7, 9, 17)
- Antiseptic (3, 7, 11, 17, 18)
- Antioxidant (15, 19, 20)
- Anti inflammatory (3, 9, 15, 18)
- Anti-viral (6, 17)
- Haemostatic (17, 18)
In vitro studies examined the antioxidant activity of Quercus robur and its role as a free radical scavenger. As a singlet oxygen scavenger Quercus robur exhibited the highest activity out of seven plant extracts tested (Aesculus hippocastanum, Hamamelis virginiana, Polygonum cuspidatum, Rosmarinus officinalis, Salivia officinalis, Sanguisorba officinalis), quenching singlet oxygens more effectively than ascorbic acid and sodium azide (19). An ethanol: water (2:3) extract of Quercus robur leaves also exerted a high potency to scavenge reactive oxygen species (superoxide radical, hydroxyl radical, peroxyl radical, hydrogen peroxide, singlet oxygen and reactive nitrogen species) (21). Additionally, Quercus robur exhibited a strong protective activity on cell damage induced by active oxygens (19).
The anti-thrombin and anti-cancer activity of methanol extracts prepared from Quercus robur were examined in vitro using mouse leukaemia cells to screen the extracts for activity against cancer. The methanol extracts of Quercus robur demonstrated high activity against both thrombin and cancer (22).
The effects of the tannin content of Quercus robur on worms of the gastrointestinal tract were tested in vitro. The effects were measured on 3rd-stage larvae and adult worms (including Teladorsagia circumcincta, Haemonchlus contortus and Trichostrongylus colubriformis species) with significant inhibitory effects obtained at both stages. In order to assess the activity of tannins, polyethylene glycol (PEG), an inhibitor of tannins, was added to oak extracts. Without PEG, significant inhibitory effects on 3rd-stage larvae and adult worms were seen. After addition of PEG, the larval migration and motility of adult worms were restored in most cases. This suggests that the tannin content of Quercus robur is partly responsible for the effects (23).
Clinical Outcome Studies
No clinical human studies have been conducted on Quercus robur as of this time.
- Diarrhoea (3, 4, 5, 15, 18)
- Dysentery (3, 4, 5, 10, 11, 18)
- Tonsillitis (3, 5)
- Haemorrhoids (3, 4, 5, 7, 14, 15, 17, 18, 25)
- Leucorrhoea (3, 4, 7, 9, 17, 18)
- Eczema/dermatitis (13, 17, 18, 25)
- Haemorrhage (9, 14, 17, 18)
Contra-indications and Cautions
- Contraindicated for external use with significant skin surface damage (1, 2, 6).
- Baths with significant amounts of oak tea are contraindicated in weeping eczema and extensive skin damage, febrile and infectious disorders, cardiac insufficiency stages III and IV and hypertonia stage IV (2, 6, 8, 18).
- Constipation (3, 15).
- Do not take internally for extended periods of time (5, 18).
- Absorption of alkaloids and alkaline drugs may be inhibited or reduced (6, 18).
- 1-2 ml of a 1:5 tincture in 60% EtOH taken 3 times daily (3).
- Decoction made from 1 teaspoon of bark in 1 cup of water. Bring to the boil and simmer for 10-15 minutes (3, 18, 25).
- For bath preparations 5g of bark is added per litre of water (8, 18).
- For compresses 20g bark is added for every litre of water (18).
- Internally 1 gram of the dried bark is to be taken 3 times daily (8).
- Galls are used in smaller quantities in place of the bark (5).
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13. Scudder J. 1870. Specific Medication and Specific Medicines. Accessed 15 September 2008 <http://www.henriettesherbal.com/eclectic/spec-med/ >.
14. Cook. 1869. The Physiomedical Dispensatory. Accessed 16 September 2008. <http://www.henriettesherbal.com/eclectic/cook/>.
15. Mills S, Bone K. 2000. Principles and Practice of Phytotherapy. Edinburgh: Churchill Livingstone.
16. Salminen JP, Roslin, T, Karonen M., Sinkkonen J, Pihlaja K, Pulkkinen P. Seasonal variation in the content of hydrolyzable tannins, flavonoid glycosides, and proanthocyanidins in oak . leaves. Journal of Chemical Ecology. 2004;30(9):1693-1711.
17. Willard T. 1993. Textbook of Modern Herbology; 2nd Revised Edition. C.W Progressive Publishing Group Inc. Canada.
18. Duke JA, Bogenshutz-Godwin MJ, duCellier J, Duke PK. 2002. Handbook of Medicinal Herbs: Second Edition. CRC Press. USA.
19. Masaki H, Sakaki S, Atsumi T, Sakurai H. Active-oxygen scavenging activity of plant extracts. Biological & Pharmaceutical Bulletin. 1995;18(1):162-166.
20. McCune LM, Johns T. Antioxidant activity in medicinal plants associated with the symptoms of diabetes mellitus used by the indigenous peoples of the North American boreal forest. J Ethnopharmacol. 2002;82(2-3):197-205.
21. Almeida IF, Fernandes E, Lima J, Costa PC, Bahia MF. Protective effect of Castanea sativa and Quercus robur leaf extracts against oxygen and nitrogen reactive species. Journal of Photochemistry And Photobiology. 2008;91(2-3):87-95.
22. Goun EA, Petrichenko VM, Solodnikov SU, Suhinina TV, Kline MA, Cunningham G. Anticancer and antithrombin activity of Russian plants. Journal Of Ethnopharmacology. 2002;337-342.
23. Paolini V, Fouraste I, Hoste H. In vitro effects of three woody plant and sainfoin extracts on 3rd-stage larvae and adult worms of three gastrointestinal nematodes. Parasitology. 2004;129(Pt 1):69-77.
24. Mammela P, Savolainen H, Lindroos L, Kangas J, Vartiainen T. Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry. Journal of Chromatography. 2000;891(1):75-83.
25. Weiss RF, Fintelmann V. 2000. Herbal Medicine. 2nd Edition. Stuttgart: Thieme.
This monograph was authored in 2008 by Ebony Prins, a student in Southern Cross University’s Bachelor of Naturopathy programme, and edited by Nena Aleschewski BNat. While the author and editor have strived to cite published information accurately, Southern Cross University will not be responsible for any inaccuracies that may have occurred.
This information is provided for educational purposes only and does not constitute medical advice. If you wish to use herbal medicine as part of your health care, seek the advice of an appropriately qualified practitioner.